Supervisory Control and Data Acquisition (SCADA) systems and more recently advanced communication systems facilitate efficient, economic and reliable operation of power systems [1]}. For instance, the communication system transmits the measurements to a state estimator that evaluates the operational status of the system accurately [2]}. However, the integration between the physical layer and the cyber layer exposes the system to cybersecurity threats.
Cyber incidents highlight the vulnerability of power systems to sophisticated attacks. To ensure the security and reliability of power system operation, it is essential to quantitatively characterize the vulnerabilities of the system in order to set up appropriate security mechanisms [3]}. To that end, security metrics provide operationally meaningful vulnerability descriptors and identify the impact that security threats pose to the system. Moreover, security metrics enable operators to assess the defence mechanisms requirements to be embedded into cybersecurity policies, processes, and technology [4]}. For example, the Common Vulnerability Scoring System (CVSS) analysis Information Technology (IT) system [5]}. Typical security metrics for power systems focus on integrity, availability, and confidentiality as envisioned by the cybersecurity working group in the NIST Smart Grid interoperability panel [6]}.
System security objectives are categorized into system vulnerability, defence power, attack severity, and situations to develop security metrics in a systematic manner [7]}.
A cyberphysical security assessment metric (CP-SAM) based on quantitative factors is proposed to assess the specific security challenges of microgrid systems [8]}.
